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configurations of DPSK and DQPSK transmitters.

Figure 47 configurations of DPSK and DQPSK transmitters.

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Figure 1. Transmission functions of: (a) EAMs and (b) MZMs transmitter packages.
Figure 1. Transmission functions of: (a) EAMs and (b) MZMs transmitter packages.
Figure 2. Attenuation of a standard single mode fiber. The solid line represents the typical shape observed in the 90’s, the dashed line represents the actual shape shape in Figure 2.
Figure 2. Attenuation of a standard single mode fiber. The solid line represents the typical shape observed in the 90’s, the dashed line represents the actual shape shape in Figure 2.
of optical signal travel slower than low-frequency components. exhibit normal dispersion. In the normal-dispersion regime, high-frequency components
of optical signal travel slower than low-frequency components. exhibit normal dispersion. In the normal-dispersion regime, high-frequency components
Figure 4. Dispersion profile of various type of fiber. SMF: single mode fiber, DSF: dispersion shifted
Figure 4. Dispersion profile of various type of fiber. SMF: single mode fiber, DSF: dispersion shifted
Figure 5. Phenomenon of Self Phase Modulation (SPM)
Figure 5. Phenomenon of Self Phase Modulation (SPM)
inherent property of FWM which is particularly useful [14]-[16].
inherent property of FWM which is particularly useful [14]-[16].
Table 1. Parameters of commercial fibers at 1550 nm according to [18]
Table 1. Parameters of commercial fibers at 1550 nm according to [18]
Figure 7. PMD effect on an optical pulse
Figure 7. PMD effect on an optical pulse
Figure 10. Raman gain coefficient versus frequency difference between signal and pump signal is 13 THz lower frequency than the pump then dropping rapidly. gnal and pump. Gain increase linearly with frequency difference peaking when the
Figure 10. Raman gain coefficient versus frequency difference between signal and pump signal is 13 THz lower frequency than the pump then dropping rapidly. gnal and pump. Gain increase linearly with frequency difference peaking when the
the bands covered by different technologies. Figure 12. Amplification bands covered by various amplification technologies ((20], [21]) where doped fiber is pumped remotely via transmission fiber. Figure 12 gives an idea of Figure 11 shows one of the many possible configuration for hybrid Raman amplifier
the bands covered by different technologies. Figure 12. Amplification bands covered by various amplification technologies ((20], [21]) where doped fiber is pumped remotely via transmission fiber. Figure 12 gives an idea of Figure 11 shows one of the many possible configuration for hybrid Raman amplifier
Figure 14. RZ modulation scheme: (a) Block diagrams of RZ transmitter (b) Waveform for intensity I(t) and (c) phase ®(t) Usually a clock signal with the same data-rate as electrical signal is used to carve RZ
Figure 14. RZ modulation scheme: (a) Block diagrams of RZ transmitter (b) Waveform for intensity I(t) and (c) phase ®(t) Usually a clock signal with the same data-rate as electrical signal is used to carve RZ
Figure 15. Bias setting of pulse carver for 33% RZ and 50% RZ
Figure 15. Bias setting of pulse carver for 33% RZ and 50% RZ
Figure 16. (a) CS-RZ transmitter setup, (b) Bias setting of pulse carver for 67% duty-cycle CSRZ phase in a CSRZ signal is periodic at half the data rate, the CSRZ spectrum exhibits
Figure 16. (a) CS-RZ transmitter setup, (b) Bias setting of pulse carver for 67% duty-cycle CSRZ phase in a CSRZ signal is periodic at half the data rate, the CSRZ spectrum exhibits
The cutoff frequency of the LPF equals a quarter of the bit rate. This is also called
The cutoff frequency of the LPF equals a quarter of the bit rate. This is also called
signal is converted to two level optical signal (see Figure 19). are transmitted as +E and -E electrical filed respectively. Thus three level electrical three values can not occur. For example, in NRZ a data sequence of {1 0 1} is mapped to
signal is converted to two level optical signal (see Figure 19). are transmitted as +E and -E electrical filed respectively. Thus three level electrical three values can not occur. For example, in NRZ a data sequence of {1 0 1} is mapped to
Table 2. An example of transformation of data in a duobinary system can see that “1”’s separated by odd number of “0’’s has opposite phase shifts. modulation format is characterized by phase inversion in the pulses triggered by the
Table 2. An example of transformation of data in a duobinary system can see that “1”’s separated by odd number of “0’’s has opposite phase shifts. modulation format is characterized by phase inversion in the pulses triggered by the
alternate mark inversion (AMI).
alternate mark inversion (AMI).
bits in the optical carrier. Signal intensity is always constant in NRZ-DPSK. data bits while digital “0” is presented by no phase change between the consecutive data
bits in the optical carrier. Signal intensity is always constant in NRZ-DPSK. data bits while digital “0” is presented by no phase change between the consecutive data
Figure 23. DPSK receiver: (a) Direct detection (b) Balanced detection Because of its constant optical power the performance of NRZ-DPSK is less susceptible into a 3-dB reduction in OSNR. Direct detection using one of MZ-DI port can also be
Figure 23. DPSK receiver: (a) Direct detection (b) Balanced detection Because of its constant optical power the performance of NRZ-DPSK is less susceptible into a 3-dB reduction in OSNR. Direct detection using one of MZ-DI port can also be
signal with the second DPSK optical signal, and then, this optical signals is modulated by a same data-rate clock
signal with the second DPSK optical signal, and then, this optical signals is modulated by a same data-rate clock
Figure 25. A typical DQPSK modulation scheme is most conveniently implemented by two parallel MZMs operated as phase modulators.
Figure 25. A typical DQPSK modulation scheme is most conveniently implemented by two parallel MZMs operated as phase modulators.
Figure 28. Experimental setup for modified duobinary RZ generation is received by an APD receiver with 8GHz bandwidth.
Figure 28. Experimental setup for modified duobinary RZ generation is received by an APD receiver with 8GHz bandwidth.
Figure 29. Principle of modified duobinary RZ generation 1 bit or 100ps, a MD-NRZ signal is generated and the duty cycle is one.
Figure 29. Principle of modified duobinary RZ generation 1 bit or 100ps, a MD-NRZ signal is generated and the duty cycle is one.
varying duty ratios. signal is approximately 25ps. Figure 31 shows optical spectra of these signals with
varying duty ratios. signal is approximately 25ps. Figure 31 shows optical spectra of these signals with
results in next section.
results in next section.
Figure 32. (a) Measured BER when modified duobinary signal operates at RZ and NRZ format.
Figure 32. (a) Measured BER when modified duobinary signal operates at RZ and NRZ format.
Figure 33. Experimental Setup for MD-RZ repeaterless transmission over 300km of SMF-28 pattern generator is divided into two equal paths by an electrical coupler. One is delayec
Figure 33. Experimental Setup for MD-RZ repeaterless transmission over 300km of SMF-28 pattern generator is divided into two equal paths by an electrical coupler. One is delayec
Figure 34. (i) MD-RZ back-to-back eye diagram (ii) MD-RZ eye after 300km transmission over SMF (iii) Measured BER against received power for back-to-back and 300km repeaterless transmission are used to emulate fiber loss. Power penalty after 300km transmission over SMF is 2.7
Figure 34. (i) MD-RZ back-to-back eye diagram (ii) MD-RZ eye after 300km transmission over SMF (iii) Measured BER against received power for back-to-back and 300km repeaterless transmission are used to emulate fiber loss. Power penalty after 300km transmission over SMF is 2.7
Figure 35. Experimental Setup for WDM MD-RZ repeaterless transmission over 240km of SMF RZ WDM experiment is shown in Figure 35.
Figure 35. Experimental Setup for WDM MD-RZ repeaterless transmission over 240km of SMF RZ WDM experiment is shown in Figure 35.
Figure 36. Optical spectra (RW: 0.1nm): (a) before amplification and (b) after Raman amplification Raman on-off gain per channel is approximately 11 dB.
Figure 36. Optical spectra (RW: 0.1nm): (a) before amplification and (b) after Raman amplification Raman on-off gain per channel is approximately 11 dB.
Figure 37. (i) MD-RZ back-to-back eye diagram (ii) MD-RZ eye diagram after 240km transmission over SMF (iii) Measured BER for back-to-back transmission and 240km repeaterless transmission over 240km of fiber are also measured and shown.
Figure 37. (i) MD-RZ back-to-back eye diagram (ii) MD-RZ eye diagram after 240km transmission over SMF (iii) Measured BER for back-to-back transmission and 240km repeaterless transmission over 240km of fiber are also measured and shown.
Table 3. Common simulation parameters
Table 3. Common simulation parameters
Figure 39. Q value as a function of input power We set SMF-28 length to be 220km and Q values are plotted against input power. Ul; and Uo are the mean values for logical “Is” and “Os”, o; and oo are their corresponding
Figure 39. Q value as a function of input power We set SMF-28 length to be 220km and Q values are plotted against input power. Ul; and Uo are the mean values for logical “Is” and “Os”, o; and oo are their corresponding
Results are shown in Figure 40. maximum transmission distance is plotted against input power for BER value of 10” levels. At 17dBm, the maximum transmission length of our scheme is approximately
Results are shown in Figure 40. maximum transmission distance is plotted against input power for BER value of 10” levels. At 17dBm, the maximum transmission length of our scheme is approximately
Figure 41. Repeaterless transmission distance techniques are employed. There is no much difference in performance between MDRZ-1
Figure 41. Repeaterless transmission distance techniques are employed. There is no much difference in performance between MDRZ-1
by using the 12.5 Gb/s BERT. Figure 42. Experimental setup for RZ-DQPSK transmitter and receiver versus the optical power entering into the receiver (i.e. the received power) was measured
by using the 12.5 Gb/s BERT. Figure 42. Experimental setup for RZ-DQPSK transmitter and receiver versus the optical power entering into the receiver (i.e. the received power) was measured
Figure 43. Measured BER at one tributary of the 100 Gb/s RZ-DQPSK signal under different conditions can help us achieve more SE high bit-rate WDM systems. help the transmission even in the presence of narrow band optical filters, which in turn
Figure 43. Measured BER at one tributary of the 100 Gb/s RZ-DQPSK signal under different conditions can help us achieve more SE high bit-rate WDM systems. help the transmission even in the presence of narrow band optical filters, which in turn
plotted against FSR/R ratio for each filter for better visualization.
plotted against FSR/R ratio for each filter for better visualization.
Figure 45. Transmission plot for the constructive port for MZ-DI with FSR/R=1 and 1.17 at 42.8 Gbps There is a sharp increase in penalty for FSR smaller than half-bit in plots and this FSR results in increased width of DI which helps in relieving the degradation due to
Figure 45. Transmission plot for the constructive port for MZ-DI with FSR/R=1 and 1.17 at 42.8 Gbps There is a sharp increase in penalty for FSR smaller than half-bit in plots and this FSR results in increased width of DI which helps in relieving the degradation due to
Figure 46. Relative Q penalty vs. FSR/R, a) 50Gb/s NRZ-DQPSK, b) 50Gb/s RZ-DQPSK optimal FSR in case of NRZ pulse shape, results in more penalty than RZ pulse shape.
Figure 46. Relative Q penalty vs. FSR/R, a) 50Gb/s NRZ-DQPSK, b) 50Gb/s RZ-DQPSK optimal FSR in case of NRZ pulse shape, results in more penalty than RZ pulse shape.
Figure 47. Simulated Eye diagrams for 100 Gb/s RZ-DQPSK with 0.40R optical filter a) I Branch, b) Q Branch RZ/NRZ DQPSK signals. Similar observations can be made from this plot as well.
Figure 47. Simulated Eye diagrams for 100 Gb/s RZ-DQPSK with 0.40R optical filter a) I Branch, b) Q Branch RZ/NRZ DQPSK signals. Similar observations can be made from this plot as well.
Figure 48. Experimental setup for DPSK transmitter and receiver generated from a 40Gbit/s pattern generator. Pseudorandom bit sequence (PRBS) lengt
Figure 48. Experimental setup for DPSK transmitter and receiver generated from a 40Gbit/s pattern generator. Pseudorandom bit sequence (PRBS) lengt
Figure 49. Experimental setup for DQPSK transmitter and receiver 50 Gb/s RZ-DQPSK signal generated in this manner is detected by a DQPSK receiver modulation depth of other modulator is set to 2/2 by adjusting bias point and driving
Figure 49. Experimental setup for DQPSK transmitter and receiver 50 Gb/s RZ-DQPSK signal generated in this manner is detected by a DQPSK receiver modulation depth of other modulator is set to 2/2 by adjusting bias point and driving
setup is shown in Figure 50 and Figure 51.
setup is shown in Figure 50 and Figure 51.
Figure 52. Measured power penalties vs. wavelength offset for 40 Gb/s DPSK signals wavelength offset of 0.04nm.
Figure 52. Measured power penalties vs. wavelength offset for 40 Gb/s DPSK signals wavelength offset of 0.04nm.
varied from 0.5 to 1.5. BER is 10° when Q value is 6.
varied from 0.5 to 1.5. BER is 10° when Q value is 6.
Figure 57. Q value versus SMF length for 8 x 40 Gb/s RZ-DPSK signals with different MZ-DI delay and duty-cycle: a) 33% RZ-DPSK (b) 50% RZ-DPSK (c) 66% RZ-DPSK
Figure 57. Q value versus SMF length for 8 x 40 Gb/s RZ-DPSK signals with different MZ-DI delay and duty-cycle: a) 33% RZ-DPSK (b) 50% RZ-DPSK (c) 66% RZ-DPSK
against SMF length for varying MZ-DI delay at the receiver.
against SMF length for varying MZ-DI delay at the receiver.
NRZ signal seems more robust in case of inaccurate MZ-DI delay as compared to RZ
NRZ signal seems more robust in case of inaccurate MZ-DI delay as compared to RZ
Figure 59. Configuration of transmitter setup a) RZ-DQPSK (b) RZ-DPSK c) MD-RZ numerical simulation. System performance is evaluated by eye opening penalty (EOP).
Figure 59. Configuration of transmitter setup a) RZ-DQPSK (b) RZ-DPSK c) MD-RZ numerical simulation. System performance is evaluated by eye opening penalty (EOP).
Figure 60. System setup for 8 x 40 Gb/s over NX100 km of SMF-28 transmission 28 which is compensated by dispersion compensation fiber (DCF).
Figure 60. System setup for 8 x 40 Gb/s over NX100 km of SMF-28 transmission 28 which is compensated by dispersion compensation fiber (DCF).
for 8x40 Gb/s MD-RZ, RZ-DPSK, RZ-DQPSK signals.
for 8x40 Gb/s MD-RZ, RZ-DPSK, RZ-DQPSK signals.
and MD-RZ signals, they can be transmitted over 1800, 1600 and 1300 km, at a BER of data rate. The narrow spectrum improves the transmission performance in DQPSK anc
and MD-RZ signals, they can be transmitted over 1800, 1600 and 1300 km, at a BER of data rate. The narrow spectrum improves the transmission performance in DQPSK anc
greater EOP due to adjacent signals.
greater EOP due to adjacent signals.
drive dual-arm modulator for the generation of RZ-DPSK signal. into two paths and then added after introducing time delay to generate two RF signals to
drive dual-arm modulator for the generation of RZ-DPSK signal. into two paths and then added after introducing time delay to generate two RF signals to
Figure 66. EOP versus average fiber input power per channel for 8x40 GB/s WDM transmission dB higher for proposed scheme. performance for lower span length but for larger span length EOP is approximately 0.5
Figure 66. EOP versus average fiber input power per channel for 8x40 GB/s WDM transmission dB higher for proposed scheme. performance for lower span length but for larger span length EOP is approximately 0.5
Figure 67. Simulated residual dispersion dependence of EOP after 500km SMF transmission transmission.
Figure 67. Simulated residual dispersion dependence of EOP after 500km SMF transmission transmission.
Figure 68. Eye pattern for 8 x 40 Gb/s WDM transmission (50GHz spacing) after 1000km of SMF
Figure 68. Eye pattern for 8 x 40 Gb/s WDM transmission (50GHz spacing) after 1000km of SMF
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